I study the gas phase metallicity (O/H) radial profiles in a representative sample of 550 nearby star forming galaxies with resolved spectroscopic data from the SDSS-IV MaNGA survey. Using strong-line ratio diagnostics (R23 and O3N2) and referencing to the effective (half-light) radius (Re), I find that the metallicity gradient steepens with stellar mass going from log(M/Mȯ) = 9.0 to log(M/Mȯ) = 10.5. At higher masses a flattening of the metallicity radial profile is observed in the central regions (R < 1Re). These findings are in agreement with recent independent analysis of other large samples of nearby galaxies.

Far-infrared photometric observations from the Herschel Space Observatory offer the opportunity to study the dust-to-gas ratio at a resolved scale in nearby galaxies. The amount, and gradient, of solid-phase metals can thus be compared with metallicity measurements in the gas phase. We describe our preliminary work on the topic with data from the DustPedia project.

Radial metallicity gradients measured today in the interstellar medium (ISM) and stellar components of disk galaxies are the result of chemo-dynamical evolution since the beginning of disk formation. This makes it difficult to infer the disk past without knowledge of the ISM metallicity gradient evolution with cosmic time. We show that abundance gradients are meaningful only if stellar age information is available. The observed gradient inversion with distance from the disk mid-plane seen in the Milky Way can be explained as the effect of inside-out disk formation and disk flaring of mono-age populations. A novel recent method is presented for constraining the evolution of the Galactic ISM metallicity with radius and time directly from the observations, while at the same time recovering the birth radii of any stellar sample with precise metallicity and age measurements.

The chemical abundances of the gas-phase and stellar components of disc galaxies are relevant to understand their formation and evolution. It has been shown that an inside-out disc formation yields negative chemical profiles. However, a large spread in metallicity gradients, including positive ones, has been reported by recent and more precise observations, suggesting the action of other physics processes such as gas outflows and inflows, radial migration, and mergers and interactions. Cosmological simulations that includes chemical models provide a tools to tackle the origin of the metallicity profiles and the action of those processes that might affect them as a function of time. I present a summary of the current state-of-knowledge from a numerical point of view and discuss the main results from the analysis of the EAGLE simulations.

The time evolution of the radial metallicity gradient is one of the most important constraints for Milky Way chemical and chemo-dynamical models. In this talk we reviewed the status of the observational debate and presented a new measurement of the age dependence of the radial abundance gradients, using combined asteroseismic and spectroscopic observations of red giant stars. We compared our results to state-of-the-art chemo-dynamical Milky Way models and recent literature results obtained with open clusters and planetary nebulae, and propose a new method to infer the past history of the Galactic radial abundance profile.

Hii regions in galaxy disks can be used as a powerful tool to trace the radial distribution of several of their properties and shed some light on the different relevant processes on galaxy formation and evolution. Among the properties that can be extracted from the study of the ionized gas are the metallicity, the excitation and the hardness of the ionizing field of radiation. In this contribution we focus on the determination of both the ionization parameter (U) and the effective temperature of the ionizing clusters (T) by means of a bayesian-like comparison between the observed relative fluxes of several emission-lines with the predictions from a set of photoionization models. We also show the implications that the use of our method has for the study of the radial variation of both U and T in some very well-studied disk galaxies of the Local Universe.

Using 3D spectroscopy data from the TYPHOON Project (PI: B. Madore), I show convincing observational evidence that the ISM oxygen abundance traced by HII regions presents systematic azimuthal variations in NGC 1365 and NGC 2997. I discuss a possible physical origin and on-going efforts to explore the prevalence and cause of such variations.

This study has been published in Sánchez-Menguiano et al. (2018). We encourage the reader to that article for more details on the study and the results.

We present an analysis of the stellar and gaseous metallicity gradients in a sample of 260 disc galaxies from the CALIFA survey. The slope of the different components are compared with the main characteristics of the galaxies, such as mass, morphology, presence of a bar, or gas fraction.

Interactions and mergers have been known as key scenarios to enhance global star formation rates and to lower the metal content of galaxies. However, little is known on how interactions affect the spatial distribution of gas metallicities. Thanks to the SDSS-IV MaNGA survey we are able to statistically constrain the impact of interactions across the optical distributions of galaxies. In this study, we compare the radial distribution of the ionized gas metallicity from a sample of 329 interacting objects – covering different interaction stages – with a statistical robust control sample. Our results suggest that galaxies close to coalesce tend to have flat, lower metallicities than non-interacting star-forming galaxies.

We analyse the evolution with redshift of the radial gradient of oxygen abundances in spiral disks resulting from our MULCHEM chemical evolution models, computed for galaxies of different sizes or masses, studying the relationships between the gradients and galaxy characteristics as the stellar mass, the size, the gas fraction or the star formation rate for z < 4.

By compiling abundances from red and blue supergiants (SGs) within the Local Universe, I present the Mass-Metallicity relation (MZR) using stellar tracers, demonstrating the excellent internal consistency. Comparing this result with nebular tracers, those empirically calibrated to direct-method studies provide the most consistent results.

We studied Planetary Nebulae (PNe) metallicity gradients using Ar abundances. We compared them with H ii regions in the galaxies of the local universe M 31, M 33, NGC 300 and in the Milky Way. Galactocentric radio (RG) and chemical abundances were collected from the literature, carefully selecting an homogeneous sample for each galaxy. In these galaxies, metallicity gradients computed with PNe abundances are flatter than those of H ii regions.

We present gas-phase metallicity gradients of 84 star-forming galaxies between 0.08 < z < 0.84. Using the galaxies with reliably determined metallicity gradients, we measure the median metallicity gradient to be negative ( $\[ - 0.039_{ - 0.009}^{ + 0.007}{\kern 1pt} dex/kpc\]$ ). Underlying this, however, is significant scatter: (8 ± 3)% [7] of galaxies have significantly positive metallicity gradients, (38 ± 5)% [32] have significantly negative gradients, (31 ± 5)% [26] have gradients consistent with being flat. (The remaining (23 ± 5)% [19] have unreliable gradient estimates.)

. Metallicity gradients are most frequently investigated directly from galaxies observed in emission. We have shown that galaxies detected via strong quasar absorption lines also exhibits a metallicity gradient in the outskirts and circumgalactic medium out to ~40 kpc distance. We infer a metallicity gradient of −0.022 dex kpc−1 for absorption-selected systems at redshifts 0.1 z 3. Applying this metallicity gradient and a flattening of the gradient beyond 12 kpc, we demonstrate that absorption-selected galaxies obey the same mass-metallicity relation (MZR) as observed for luminosity-selected galaxies.

We present reconstructed source plane metallicity maps for a sample of ~30 gravitationally lensed galaxies between 1.2 < z < 2.5, observed in the framework of the KLEVER Survey. Oxygen abundance is derived exploiting a variety of different emission line diagnostics, as provided by the full coverage of the near-infrared bands. The majority of galaxies in our sample present flat radial metallicity gradients, in agreement with galaxy evolution models predicting strong feedback mechanisms in place at these epochs. However, complex patterns as seen in some of our metallicity maps warn against the use of azimuthally-averaged radial gradients as the only observable to constrain chemical evolution models.

We have combined data of the DustPedia project with observations of gas components of the interstellar medium (ISM) and metallicity abundances for late-type DustPedia galaxies to definitively characterize the ISM scaling relations in the Local Universe. In particular, we have focused on the comparison of the dust-to-gas mass ratio with gas phase metallicities.

There is a growing evidence that our Sun was born in a rich cluster that also contained massive stars. Therefore, the study of high-mass star-forming regions is key to understand our chemical heritage. In fact, molecules found in comets, in other pristine Solar System bodies and in protoplanetary disks, are enriched in 15N, because they show a lower 14N/15N ratio (100-150) with respect to the value representative of the Proto-Solar Nebula (PSN, 441 ± 6), but the reasons of this enrichment cannot be explained by current chemical models. Moreover, the 14N/15N ratio is important because from it we can learn more about the stellar nucleosynthesis processes that produces both the elements. In this sense observations of star-forming regions are useful to constrain Galactic chemical evolution (GCE) models.

We are performing systematic observation studies on the Galactic interstellar isotopic ratios, including 18O/17O, 12C/13C, 14N/15N and 32S/34S. Our strategy focuses on combination of multi-transition observation data toward large samples with different Galactocentric distances. Our preliminary results show positive Galactic radial gradients of 18O/17O and 12C/13C. In both cases, the ratio increases with the Galactocentric distance, which agrees with the inside-out scenario of our Galaxy. Observations of other isotopes such as 14N/15N and 32S/34S are on-going.